Cooling system with defrost and temperature rise indicator

ABSTRACT

A defrost or thaw measuring device has a dumbbell or hourglass-shaped rotatable compartment with a cavity, the cavity being partly filled with at least two phase change materials having different melting points. The measuring device may determine the time period of thawing at two or more temperature intervals in the refrigeration space.

BACKGROUND OF THE INVENTION Field of the Invention

The application relates to the preservation and/or evaluation of frozenitems, particularly foodstuffs, subject to warming from a cooled status.

Description of the Related Art

For cooled materials, particularly those subject to cooling by a powersource, such as an electricity grid, losses of power can lead tosuspensions of cooling and potentially damaging thawing of the cooledmaterial(s). For example, when a person is underway and/or away from thesite of the cooled material(s), such as traveling or working,electricity at home could be interrupted or cut off for periods ofminutes, hours, or even days, which may, for example, affectrefrigerated and frozen food in the refrigerator or freezer. When thepower comes back on, it can happen that the food is chilled and/orrefrozen without a person's noticing the outage or period of suspendedcooling.

This scenario can apply to any type of cooling equipment, such as infactories, storage facilities, or sales points (e.g., supermarkets).With current refrigerators, an operator / owner cannot easily noticeand/or determine if the food has been thawed or exposed to an increasein temperature. Attempts have been made to address this situation.

CH 625618 to Bekhechi discloses an apparatus for checking and monitoringthe temperature prevailing inside a freezer consisting of a receptaclein the shape of an egg-timer containing a colored substance whosemelting temperature is substantially equal to a set-point temperature ofthe order of −10° C. Bekhechi's apparatus is placed in a freezer in aposition such that the substance in the solid state is separated fromthe bottom of the receptacle. In the case of reheating, Bekhechi'ssubstance liquefies and flows to the bottom of the receptacle.Bekhechi's apparatus purports to be re-usable after melting of thesubstance, in contrast to known apparatuses consisting of sphericalreceptacles containing grains of a substance which can liquefy duringreheating.

While Bekhechi appears to disclose (flattened) hour-glass shapeddevices, alongside regular tetrahedal shapes, as well as a separatinggrid or internal partition between two chambers, Bekhechi's device hasno means of installation inside the refrigerator and Bekhechi fails toexplain whether the device can be used inside the freezer. In addition,Bekhechi's device cannot be rotated and cannot measure the period ofcooling interruption, i.e., how long the food was subjected tonon-cooled, higher temperature.

FR 267 6532 attempts to solve the cooling suspension problem with acomplex design and requires filling with water from above, which maycause leakage. In addition, FR 267 6532 does not explain how to disposeof melted water from the lower chamber before filling the upper one, andit likewise fails to measure the number of hours in which thetemperature has increased.

U.S. Pat. No. 9,410,730 to Keefe discloses a container with a poroussupport member affixed inside the container, defining upper and lowerchambers, and a liquid partly filling the container. The liquid isfrozen in the upper chamber. Keefe's container is oriented so that theupper chamber is gravitationally above the lower chamber, wherein thefrozen liquid remains in the upper chamber. Keefe's container is placedin a cold zone of a freezer, and the presence of the liquid in Keefe'slower chamber indicates that a thaw episode has occurred. Keefe'sindicator includes a container with an inner space, which is dividedinto an upper chamber and a lower chamber by a porous support member,wherein a liquid with a colored marker partly fills the inner space.Keefe's indicator can include a graduated scale that is placed onto thecontainer wall of the indicator for measuring a depth of melt waterduring a thaw event.

However, Keefe does not suggest anything beyond a cylindrical shape forits indicator, e.g., no dumbbell-shape, and its container is not clearlyrotatable. Moreover, Keefe's device is configured to hook to a shelf ofcooling device, and hang from the shelf. Keefe's device is thus notreleasably and rotatably attached to a wall of the refrigeration space,e.g., with a pin, magnet, or the like. Keefe likewise fails to disclosetwo or more miscible phase change materials (PCMs) in the container, norPCMs suitable for determining the time period of thawing at two or moretemperature intervals.

U.S. Pat. No. 3,063,235 to Winchell discloses a transparent container ofwater or other liquid in which is transversely disposed a spider orscreen member. Winchell's device may have a pin with a ball head,connecting it near its center, to a suction cup, allowing attachment toa freezer door or wall, and inverted or turned in a vertical plane.Winchell's device may be inserted in a freezer in an inverted positionso that the water or other liquid freezes to ice located at one end ofthe container, then be turned right side up, and, if the refrigerationunit is temporarily inactive due to interruption of its power supply orfor other reasons, the ice in the container will slowly melt and thewater or other liquid will drain through the screen to the empty lowerportion of the container. The quantity of water or other liquid inWinchell's container is said to measure of the length of time that thefood has defrosted.

However, Winchell's device is generally a cylindrical or prismic shape,not a dumbbell shape container. Additionally, Winchell appears limitedto the use of one phase change material, such as water, and does notdisclose using at least two miscible PCMs in the container to be able todetermine the time period of thawing at two or more temperatureintervals.

U.S. Pat. No. 4,844,622 to Weiss discloses a resettable reusable timetemperature recording thermometer instrument for tracking and recordingtemperature excursions in commercial refrigeration environmentscomprises a closed vessel having two chambers and metering orificebetween the chambers and a time measurement/recording means with a scaleto indicate the total time duration of liquid flow through the orificefrom one chamber to the other; and an assembly of such vessels with fillliquids of different freezing point temperatures. Weiss's device(s) maybe hour-glass shaped, and optionally made of a wide variety oftranslucent or transparent materials such as glasses and plastics. Weissmay use a fill material of selected from a wide variety of organic orinorganic materials having requisite sharp melting point temperatures,preferably ethylene glycol diluted with water.

However, Weiss does not suggest attaching its device or array to anaxis, attachable to a cooling unit wall, allowing vertical rotation ofits system, nor does Weiss disclose a permeable layer between itschambers. In addition Weiss requires an equilibration tube to allow gaspressurization between its chambers. Although Weiss describes twomiscible liquids, i.e., water and ethylene glycol, Weiss uses suchsolutions to establish multiple container arrays of different meltingsharp points, rather than as a single solution or mixture of PCMs tomeasure two or more temperature intervals.

U.S. Pat. No. 5,924,294 to Tiby discloses a self-contained device andmethod for determining the variations in temperature regulatedtemperature enclosures. Tiby's device consists of a container comprisinga tank connected to a receptacle, the inner spaces of which communicatewith one another through one or two ducts of reduced or constrictedcross sections, in a sort of hour-glass shape. Tiby's container isformed at least partially of a material allowing heat transfer with theexterior and contains an initially solidified material, the meltingtemperature of which is constant and the total volume is no more thanthe overall volume of the tank and duct element.

Tiby's container can be turned upside down or pivoted through 180°, butTiby does not teach an axis upon which it could be rotated and/orattached to a wall. While Tiby discloses a means of retaining asubstance in the solid state between two chambers, Tiby does notdisclose a planar permeable barrier or frit. Instead, Tiby's substanceretainer consists of a plate with perforations or asperities, and asurface “approximately perpendicular” to gravity whose perimeter allowsthe melted substance to flow from its reservoir into a receptacle alongthe reservoir wall without directly blocking the two conduits,portraying these with vertical portions and complicated designs, beyondsimple planes. Also, while the material contained in Tiby is a eutecticthat may be a mixture of two or more constituents, Tiby's eutecticalways has a fixed melting temperature and a constant composition for agiven mixture. Tiby's substance may be in pure state, such as water, tofulfill its function, with the constancy of its melting temperature at agiven pressure when it has been frozen, rather than as a single solutionof PCMs to measure two or more temperature intervals. Tiby does notdisclose being able to determine the time period of thawing at two ormore temperature intervals with a single solution at least two(miscible) PCMs in its vessel.

US 2009/0129434 A1 by Creus and Rihoux discloses a method and device fordetecting a temperature rise, in particular a preservation temperature,in a cooler designed for preserving products, comprising liquefying adetection substance, contained in a first zone, by a temperature riseand moving the liquefied detection substance into a second zone of thechamber to enable the temperature rise to be detected. Creus's devicehas a container with a first and a second compartment, a detectionsubstance, and floating components for quantifying the displaced volumeof the liquefied detection substance to determine the rise intemperature that has occurred inside a cold chamber. Creus's device mayhave an articulated arm, attached to a suction cup, which may attach toa wall of the cold chamber and allow the device to be pivoted orinverted vertically. Creus's detection substance may be a mixture ofwater and an alcohol or a polyol, e.g., water/glycerol, awater/isopropanol; an oily substance/saccharose,water/sucrose/fructose/saccharose, or water/propylene glycol

However, Creus teaches relatively complex shapes or rectangular prism,not a dumbbell-shaped container, nor any shape which can be rotated uponan axis. In addition, Creus does not disclose at least two (miscible)PCMs in the vessel able to determine the time period of thawing at twoor more temperature intervals.

U.S. Pat. No. 4,144,834 to Donegan discloses a thaw-indicating devicethat is visibly positioned in a package of frozen food so to warn aconsumer if the food item has ever been subjected to being thawed, andthus being spoiled even if refrozen subsequently. Donegan's deviceconsists of a transparent plastic capsule having a sealed singularcompartment in one end of which there is a colorless, clear, frozen iceand in the other end of which there is a powdered dye that is soluble inwater, so that if the ice melts into water due to thawing temperaturesthe entire interior of the capsule is visibly colored. However,Donegan's defrost indicator is merely a disposable element, notconfigured to attach to a cooling device, but rather the object to becooled. Donegan's defrost indicator is not rotatable and is onlypill-shaped, i.e., cylindrical with rounded ends, for embedding in acooled product.

Previous approaches to the problems discussed above generally havecomplex designs, lack ease of rotatability and attachability onto acooling device wall, and/or do not measure of the time that the food wassubjected to increased temperature and/or suspended cooling, e.g., frominterrupted power in a cooling device, wherein the period of thawing canbe measured at two or more temperature intervals.

SUMMARY OF THE INVENTION

Devices within the scope of the invention may comprise: an elongatedcompartment including a first end and a second end separated by a sidewall along a longitudinal axis of the elongated compartment, therebyforming a cavity including a first chamber and a second chamber that arefluidly connected through a narrow section located between the first andsecond chambers, wherein at least a portion of the elongated compartmentis made of a first transparent material; a liquid, comprising a firstphase change material and a second phase change material, disposed inthe cavity; a base to which the elongated compartment is releasably androtatably attached, the base being configured to mount the elongatedcompartment to a wall; and a graduation arranged on an outside surfaceof the elongated compartment suitable for measuring a liquid level inthe elongated compartment, wherein the first and second chambers aresymmetric to each other, and wherein the device is configured todetermine a defrost time period for two or more temperature intervals ina cooled space.

Inventive devices may further comprise a planar permeable structuredisposed at the narrow section and configured to prevent a movement of asolidified liquid from one chamber to another when the elongatedcompartment is vertically oriented.

The first transparent material may comprise quartz, glass, polyethyleneterephthalate, polybutylene terephthalate, polyacrylate,polymethacrylate, polyethylene, polypropylene, polyvinyl chloride,polyethernitrile, polyethersulfone, polystyrene, polycarbonate,polymethylmethacrylate, styrene-acrylonitrile, styrene-methylmethacrylate, methyl methacrylate-butadiene-styrene, or a two or more ofany of these. The liquid may comprise water and, beyond the phasetransfer materials (PCMs), may further comprise a coloring dye.

The first and second chambers each include a cylindrical or prismicportion including a taper toward the narrow section. For example, theelongated compartment may configured in the shape of a dumbbell or anhour glass.

Inventive devices and/or elongated compartments may be configured torotate about a central axis orthogonal to the base. The base may includea single joint about which the elongated compartment is configured torotate, or the base may include a first joint and a second joint (ormore joints) about which the elongated compartment is configured torotate.

The first phase change material and the second phase change material mayeach be a hydrocarbon. The first phase change material may be an organicor inorganic salt, and the second phase change material may be water.The liquid further comprises a third phase change material. All phasechange materials in the liquid may be miscible in each other.

The two or more temperature intervals measured by the device may be in arange of from −20 to 10° C., and/or may be spaced by at least 5° C.

Inventive devices may further comprise a shell enclosing the elongatedcompartment and/or a transparent housing enclosing the device componentsin the space orthogonally outwards from the wall and base. The shelland/or the housing may be selected from the same group of transparentmaterials as the elongated compartment, and the second transparentmaterial (of the shell) and/or the third transparent material (of thehousing) may be of a different material from the first transparentmaterial (of the elongated compartment). The materials of constructionare preferably both resilient and strong to prevent breakage.

The base may comprise a magnet configured to attach the device to thewall.

Aspects of the invention provide methods of measuring a time period ofdefrosting in a refrigeration space, comprising mounting a measuringdevice, such as any device described herein, to a wall of therefrigerated space and vertically aligning the elongated compartment byrotating the elongated compartment around a pin releasably and rotatablyattached to the elongated compartment to the base, allowing the liquidto freeze in a chamber located at a bottom of the elongated compartmentto form a solidified liquid; rotating the elongated compartment aroundthe pin to substitute a position of the chamber located at the bottom ofthe elongated compartment with a chamber located at a top of theelongated compartment, wherein the solidified liquid melts when atemperature of the refrigeration space rises above a predeterminedtemperature in a range of from −20 to 10° C., and the liquid iscollected in the chamber located at the bottom of the elongatedcompartment; measuring a liquid level of the liquid that is collected inthe chamber located at the bottom of the elongated compartment with themeasuring tape; and measuring the defrost time period in the cooledspace from the liquid level.

The time period of defrosting in the refrigeration space may be measuredwith a calibration curve that correlates the liquid level to the timeperiod of defrosting.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 shows a right front perspective view of a device within the scopeof the invention;

FIG. 2 shows a right side elevational view of a device within the scopeof the invention including wall environment from a wall to which it isattached, e.g., a cooling device wall;

FIG. 3 shows a right front perspective zoomed view of a device withinthe scope of the invention, illustrating a direction of rotation about ajoint;

FIG. 4 shows a front elevation of a further measuring device within thescope of the invention having an alternate graduation and beingrotatable about a dual joint system with a track; and

FIG. 5 shows a front elevation of a further measuring device within thescope of the invention; and

FIG. 6 shows a front elevation of the measuring device of FIG. 5implementing a Galileo thermometer principle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Devices within the scope of the invention may be installed inrefrigerator, freezer, or any other cooling device, and can measure theduration of suspended cooling, often associated with a temperature rise,using, e.g., an external graduation measuring the level of meltedliquid, optionally after the melted liquid resolidifies. Approacheswithin the invention may allow the vessel to completely melt the liquidand then place the measuring device inside the cooling device until itfreezes and then turn it in place.

Inventive devices herein generally have simple designs and are easy touse. Such devices may be configured for (optionally temporary)installation in a refrigerator, freezer, or other cooling device, oreven in a preservation container, such as a common cooler or an organtransplant transporter. Inventive devices can measure the duration oftemperature rise and/or the temperature reached within the coolingdevice/cooler. Inventive measuring devices may also indicate theviability of food affected by the suspension in cooling, e.g., in hours,minutes, and/or seconds. Inventive devices allow a solidified liquidcomprising phase change materials (PCMs) to melt in an elongatedcompartment, place the elongated compartment into the coolingdevice/cooler until it freezes, then turn the measuring device in place.Alternatively, the PCM liquid can be frozen in advance, then placed intothe cooling device/cooler. The PCM liquid may be reused and need not bedisposed, and the elongated compartment may be supplied to the endconsumer in a sealed, calibrated form. Therefore, it may be unnecessaryto open and fill the measuring device, which may improve safety,cleanliness, and accuracy in measurement over known devices.

The graduation on inventive measuring devices may allow the user to knowthe value and/or duration of the temperature rise in minutes and hours.Using predetermined data on the properties of the objects to be cooled,i.e., tolerance to heat and/or temperature of particular types of food,medicine (chemical, biological, or otherwise), or biological material(tissues, blood components, gametes, biological medicine), the user mayascertain the viability (health) of the refrigerated material subject tosuspended cooling. Such viability evaluation can be determined by tablesbased upon available data on temperature-dependent storage life of thecooled material(s), or using software/applications on computerizeddevices, such as laptops, cell phones, tablets, or even directly onto anelectronic display embedded in the cooling device which accesses and/orcontains a database of the information on the thermodynamic andtemperature tolerance of the cooled materials.

Aspects of the invention provide a measurement method or device usefulfor measuring the status of the cooled materials and suitable forinstallation—temporary or permanent—in cooling devices, such asrefrigerators, freezers, or deep freezers, or in insulating containers,such as coolers, dewars, biologic tissue preservation or transportcontainer, or the like. Inventive devices and methods are useful forrecording suspended cooling and consequently viability of the cooledmaterials, particularly foods, by calculating the amount of time and/ortemperature such refrigerated materials were exposed to raisedtemperature within the cooling device, even after restoration of powerand/or cooling. That is, food could be re-chilled and/or re-frozenwithout it being recognized that an interruption of cooling occurred.Devices or methods as claimed can capture the suspended cooling event,even if the event would not have been recognizable externally to thecooling device.

Devices within the scope of the invention may comprise an elongatedcompartment including a first end and a second end separated by a sidewall along a longitudinal axis of the elongated compartment, therebyforming a cavity including a first chamber and a second chamber that arefluidly connected through a narrow section located between the first andsecond chambers, wherein at least a portion of the elongated compartmentis made of a first transparent material; a liquid, comprising a firstphase change material (PCM) and a second PCM, particularly PCMs havingdifferent melting points, disposed in the cavity; a base to which theelongated compartment is releasably and rotatably attached, the basebeing configured to mount the elongated compartment to a wall; and agraduation arranged on an outside surface of the elongated compartmentsuitable for measuring a liquid level in the elongated compartment,wherein the first and second chambers are symmetric to each other, andwherein the device is configured to determine a defrost time period fortwo or more temperature intervals in a cooled space.

The liquid and/or components thereof change phase from solid to liquiddepending upon temperature and the duration of exposure to temperaturesbeyond the melting/fusion point. While measurement of temperature andduration of exposure to higher (non-cooled) temperatures can be measuredusing inventive devices with a single phase change material (PCM), suchas water, a combination of PCMs in the liquid can allow the measurementof whether certain temperature thresholds (two, three, four, or more)have been reached, and for how long. The liquid may include two or morePCMs which are miscible in each other, which is particularly useful whena permeable membrane/mesh separates the first and second chambers, orimmiscible which is particularly useful when separation of the fluidsand corresponding solid phases is desired. All PCMs of the liquid may bemiscible, though none are required to be miscible, and it may beadvantageous to use immiscible mixtures, e.g., to employ a Galileo-typethermometer effect in the measuring device. The Galileo-thermometereffect may also be achieved by suspending in the liquid insolubleobjects of fixed density, e.g., glass spheres containing water, air,and/or chloroform. The liquid may comprise water as one of the PCMs orin addition to the PCMs. Beyond the phase transfer materials (PCMs), theliquid may further comprise a coloring dye. Exemplary PCMs, includingselected commercially available formulations/materials, which could beuseful within the scope of the invention, depending upon the temperaturethreshold of the cooling device to be monitored, are provided below inTable 1. The first PCM and the second PCM may each be a hydrocarbon. Thefirst PCM may be an organic or inorganic salt, and the second PCM may bewater. The first PCM may be an organic C2 to C22 (C3 to C18, C4 to C16,or C5 to C18) acid, and the second PCM may be a C8 to C22 (C10 to C21,C12 to C20, or C14 to C18) hydrocarbon. The liquid may further comprisea third PCM. The number of PCMs in the solution may be 2, 3, 4, 5, 6, oreven 7. At least one PCM may be aqueous with a number of inorganic PCMsand the other PCM organic comprising one or more hydrocarbons.

Especially in the case when the device comprises two PCMs that areimmiscible, a first PCM having a relatively higher melting pointpreferably has a density that is less than the density of a second PCMhaving a relatively lower melting point. In this configuration thedevice is installed with both PCM's in a liquid form as two separatedphases. The separated phases are present in a lower compartment of thedevice and are subsequently cooled until both become solid. Turning theelongated compartment by 180° after solidifications of both PCMs forms asolid mass of the two-phase mixture. Melting of the first phase at afirst critical temperature permits passage of the first phase throughthe narrow section (5) while permitting the lower melting PCM phase toremain in a solid-state in its original compartment. One or more of theimmiscible PCMs may comprise a dye that is miscible or soluble in onlyone of the PCMs.

TABLE 1 Temp Temp Temp Substance [° C.] Substance [° C.] Substance [°C.] 24.8 wt. % HCl (aq) −86 dodecane −9.6 ClimSel C 7^(f) 7 24 wt. %LiCl (aq) −67 22.1 wt. % BaCl₂ (aq) −7.7 formic acid HCOOH 7.8 30.5 wt.% CaCl₂ (aq) −49.5 triethylene glycol −7 C15-16 paraffin 8 C₆H₁₄O₄0100-Q-50 BioPCM^(a) −50 16.5 wt. % KHCO₃ (aq) −6 polyethylene glycol 8E400 0100-Q-45 BioPCM^(a) −45 STL-6 salt sol'n^(e) −6 BioPCM Q8^(a) 828.01 wt. % MgCl₂ −33.5 SN06 salt sol'n^(b) −6 LiClO₃•3H₂O 8.1 (aq) SN33salt sol'n^(b) −33 18.63 wt. % MgSO₄ −4.8 RTS paraffin^(g) 9 (aq)TH-31^(c) −31 tetradecane C₁₄H₃₀ + −4.02 pentadecane 9.9 octadecaneC₁₈H₃₈ 30.5 wt. % Al(NO₃)₃ −30.6 TH-4^(c) −4 C15 paraffin 10 (aq) MPCM(−30)^(d) −30 20.5 wt. % Na₂CO₃ −3 propyl palmitate 10 (aq) C₁₉H₃₈O₂SN29 salt sol'n^(b) −29 STL-3 salt sol'n^(e) −3 ZnCl₂•3H₂O 10 SN26 saltsol'n^(b) −26 SN03 salt sol'n^(b) −3 isopropyl palmitate 11 C₁₉H₃₈O₂27.9 wt. % Li₂SO₄ −23 6.49 wt. % K₂SO₄ (aq) −1.55 BioPCM Q12^(a) 12 22.4wt. % NaCl (aq) −21.2 4.03 wt. % Na₂SO₄ −1.2 capric-lauric acid + 13.3(aq) pentadecane (90:10) TH-21^(c) −21 water H₂O 0 isopropyl stearate 14to 18 C₂₁H₄₂O₂ SN21 salt sol'n^(b) −21 H₂O + polyacrylamide 0 ClimSelC15^(f) 15 STL-21 salt sol'n^(e) −21 91.67% tetradecane + 1.7Mn(NO₃)₂•6H₂O/ 15 to 25 8.33% hexadecane MnCl₂•4H₂O (4%) SN18 saltsol'n^(b) −18 tetradecane + 1.5 to 5.6 NaOH•3.5H₂O 15.2 docosane (C22)TH-16^(c) −16 Tetradecane + 3.5 to 5.5 caprylic acid C₈H₁₆O₂ 16.3heneicosane (C21) STL-16^(e) −16 BioPCM Q4^(a) 4 DMSO (CH₃)₂SO 16.5 SN15salt sol'n^(b) −15 31 wt. % Na₂SO₄, 13 4 C16 paraffin 16.7 wt. % NaCl,16 wt. % SN12 salt sol'n^(b) −12 C14 paraffin 4.5 to 5.5 acetic acidC₂H₄O₂ 16.7 STLN10 salt sol'n^(e) −11 tetrahydrofuran 5 glycerin 17.9C₄H₈O SN10 salt sol'n^(b) −11 BioPCM Q5^(a) 5 NaCl•Na₂SO₄•10H₂O 18 19.7wt. % KCl −10.6 tetradecanes 5.5 polyethylene glycol 20 E600 diethyleneglycol −10.5 n-tetradecane 5.8 to 5.9 C16-18 paraffin 20 to 22 C₄H₁₀O₃TH-10^(c) −10 BioPCM Q6^(a) 6 C17 paraffin 21.7 6 wt. % KCl (aq) −10^(a)Phase Change Energy Solutions, Inc.; ^(b)Cristopia; ^(c)TEAP;^(d)Microtek Labs, Inc.; ^(e)Mitsubishi Chemical Corporation;^(f)Climator Sweden AB; ^(g)Rubitherm GmbH

Further relevant PCMs will be known to the person of skill in the art,for example, from Appl. Thermal Eng. 2003, 23, 251-283, Renewable &Sustainable Energy Rev. 2009, 13, 318-345, and Appl. Energy 2012, 99,513-533, each of which are incorporated in their entirety herein. AnyPCM system may be useful herein, though particular value may be found inPCM systems suitable to assess a thaw at two or more temperatureintervals.

The two or more temperature intervals measured by the device may be in arange of from −80 to 30° C., −50 to 20° C., −40 to 15° C., or −20 to 10°C. The temperatures measured by the measuring device will depend uponthe material to be monitored, though most biological materials will havetemperature targets of at most 10° C., or at most 7.5° C., 5° C., 2.5°C., 2° C., 1° C., 0° C. or −1° C. Of course, biological materials maynot be infinitely coolable, so relevant bottom temperature targets maybe −40° C., −30° C., −25° C., −20° C., of −15° C. The temperatures ofthe two temperature intervals may be spaced by 2.5° C., 5° C., 7.5° C.,10° C., or 15° C. The PCM liquid as used in measuring device typicallydoes not have a single melting point.

The first PCM may have a melting/fusion point of about −20° C., −15° C.,−10° C., −5° C., or 0° C., and the second PCM may have a melting/fusionpoint of about −15° C., −10° C., −5° C., 0° C., 5° C., or 8° C. Anyvalue listed in Table 1 could be relevant melting points for PCMsherein, and, given that PCMs are presently being developed to targetevery temperature across the spectrum, particularly for refrigeration,freezing, and deep freezing applications, a person of skill in the artwill readily recognize that devices according to the invention may betailored to particular temperature ranges, taking into consideration theapplication under consideration. For example, the PCM selection willgenerally differ for monitoring frozen proteins or antibody samples,versus applications for frozen vegetables, ice cream, or even milk, orstill further general household refrigeration. Industrial cooling orfreezing operators may thus coordinate with a manufacturer of ameasuring device as described herein to prepare a tailored monitoringdevice.

Inventive devices may further comprise a planar permeable structure,such as a glass frit, a wire net, a mesh, a permeable plastic membrane(PE, PP, PTFE, PVDF, etc.), disposed at the narrow section andconfigured to prevent a movement of a solidified liquid from one chamberto another when the elongated compartment is vertically oriented.

The first transparent material of the elongated compartment, or thesecond or third transparent materials of the optional shell and/orhousing, may comprise quartz, glass, polyethylene terephthalate,polybutylene terephthalate, polyacrylate, polymethacrylate,polyethylene, polypropylene, polyvinyl chloride, polyethernitrile,polyethersulfone, polystyrene, polycarbonate, polymethylmethacrylate,styrene acrylonitrile, styrene methyl methacrylate, methyl methacrylatebutadiene styrene, or a two or more of any of these. Besides fusedquartz, the types of glass which may be used, depending upon thetemperature of cooling, may be soda-lime glass, borosilicate glass, leadoxide glass, aluminosilicate glass, or even germanium oxide glass. Asnoted, inventive devices may further comprise a shell enclosing theelongated compartment and/or a transparent housing enclosing the devicecomponents in the space orthogonally outwards from the wall and base.The shell and/or the housing may be selected from the same group oftransparent materials as the elongated compartment, and the secondtransparent material (of the shell) and/or the third transparentmaterial (of the housing) may be of a different material from the firsttransparent material (of the elongated compartment). Practically, it isgenerally useful when the elongated body can be easily cleaned, e.g., ina dish washer.

Inventive devices may be configured such that the first and secondchambers each include a cylindrical or prismic portion including a tapertoward the narrow section. For example, the elongated compartment may beconfigured in the shape of a dumbbell or an hour glass. As depicted inFIG. 2, the geometric shape of inventive devices may be flattened on onehalf. Inventive devices may also be substantially planar in a directionorthogonal to the wall of the cooling device/cooler, as such a designcan advantageously reduce space requirements and/or improve the accuracyof visible measurements. A horizontal cross-section of the chambers,which will generally be mirror images of each other across the verticalcenter, viewed from top to bottom, may be rectangular, hexagonal,octagonal, ovular, ovular, circular, circular, or a half-form of any ofthese, such as a half-circular cross-section. When viewed from an frontelevation in which the elongated compartment extends from top to bottom,down a central axis orthogonal to the base, the cross-section willgenerally taper toward the narrow section in a linear or curved manner.Preferred front elevational cross-sections may be hourglass or dumbbellshaped, depending upon the application, though the prominence of thewider portions may be reduced, and/or the elongated compartment furtherelongated in a top-to-bottom direction, to improve measurement accuracy.

In a simple form, an inventive measuring device may have a graduated,hourglass or dumbbell-shaped, elongated body with a single, centraljoint around which the elongated body is rotatable and with which theelongated body is detachable from a base. Such a measuring device, likeany other herein, could suitably use a single substance PCM, but mayadvantageously employ more than one PCM in a single container.

Inventive devices may be configured such the entire device and/or theelongated compartment may be rotated about a central axis orthogonal tothe base. The base may include a single joint about which the elongatedcompartment is configured to rotate, or the base may include a firstjoint and a second joint (or more joints) about which the elongatedcompartment is configured to rotate. For example, the elongated body, orthe shell and/or housing covering the elongated body, may be attachedwith three joints to the base, which are located towards the top, at thevertical center, and towards the bottom. For simplicity, a single jointmay be preferred. Guide posts or stoppers, e.g., made of elastomer suchas butadiene, silicone, SBR, nitrile, etc., may be included on the baseon either or both sides of the vertically centered rest position of theelongated body, as a guide for the user to align the measuring devicefor operation. The vertical alignment of the generally freely rotatableelongated body may be achieved by a segmented bearing joint, i.e., onethat clicks or provides tactile feedback every, e.g., 15°, 30°, 45°, or90°.

The base may take on any shape and form, but will generally tend towardsplanarity in a direction orthogonal to the wall. The base may be round,such as circular or ovular, rectangular, e.g., square, or may be in theform of one or more stripes/slabs so long as these are sufficient tohost any necessary joints, stoppers, or wall attachments. The base mayalso be tailored to particular electronic cooling devices or insulatedcoolers, e.g., snap-fitting or fitting a wall indentation. The base maybe attached to the wall in any conventional manner, and may bedetachable from the wall. For example, the base may comprise a magnet or2, 3, 4, or more magnets, configured to attach the device to the wall.Such a magnet may be ring-shaped, circular, or rectangular.

Aspects of the invention provide methods of measuring a time period ofdefrosting in a refrigeration space, comprising mounting a measuringdevice, such as any device described herein, to a wall of therefrigerated space and vertically aligning the elongated compartment byrotating the elongated compartment around a pin releasably and rotatablyattached to the elongated compartment to the base, allowing the liquidto freeze in a chamber located at a bottom of the elongated compartmentto form a solidified liquid; rotating the elongated compartment aroundthe pin to substitute a position of the chamber located at the bottom ofthe elongated compartment with a chamber located at a top of theelongated compartment, wherein the solidified liquid melts when atemperature of the refrigeration space rises above a predeterminedtemperature in a range of from −80 to 30° C., −50 to 20° C., −40 to 15°C., or −20 to 10° C., and the liquid is collected in the chamber locatedat the bottom of the elongated compartment; measuring a liquid level ofthe liquid that is collected in the chamber located at the bottom of theelongated compartment with the measuring tape; and, optionally,measuring the defrost/thaw time period in the cooled space from theliquid level.

The evaluation of the defrost time may be built into the graduation,though a “smart” cooling device may be able to better estimate the massand heat transfer properties of contents and/or environs of the coolingdevice, and, e.g., provide a prompt on an electronic screen for which auser enters a read-out from the measuring device, whereupon a databaseof food (or other cooled material) properties are consulted to directlyinstruct the user of the viability of the food (or other cooledmaterial), e.g., that the food must be discarded as spoiled, or that itsexpiration date should be shifted forward, or even that the food was notaffected.

The defrost/thaw time period of defrosting in the refrigeration spacemay be measured with a calibration curve that correlates the liquidlevel to the time period of defrosting. Such a calibration curve may be,e.g., in a handbook delivered with the measuring device and/or madeavailable on the internet. The calculation may also be conducted by anapplication on a personal electronic device or by accessing a databaseor interface on the internet, e.g., a website, which conducts thecalculation for the user. Such automated services may provide furtherentries, e.g., on the contents of the cooling device, which may improvethe accuracy of the viability evaluation. If the user is aware of thetolerable temperature for particular foodstuffs or biological materials,an indication from a dual or triad temperature interval, indicating thatone temperature was reached, but not a second or a third (consecutivelyhigher) temperature, could immediately inform the user of the viabilityof the cooled material in question.

As can be inferred, inventive measuring devices and methods may findparticular use in the cooling device(s) of households, manufacturers,hospitals, blood banks, merchants, chemical plants and retailer,commercial retailers, meat and frozen food packagers, etc.

Referring now to the drawings, wherein like reference numerals designateidentical or corresponding parts throughout the several views.

In reference to FIG. 1 through FIG. 3 inventive devices may comprise twomain parts a base 1 and an elongated compartment 2. The base 1 may beremovably (or permanently) installed on a wall 9 of a cooling apparatus,e.g., with a magnet, screw, bolt, rivet, adhesive tape/substance(optionally reversible), hook, press-lock, lock-and-key or puzzle-styleattachment, or similar affixer. The elongated compartment 2 may be atubular vessel installed on the base 1 with, e.g., a central joint 8, ortwo or more optionally symmetrically distributed joints 8.

The joint(s) 8 may allow the elongated compartment 2 to be rotated 180°,360°, and/or infinitely. Additionally, the joint(s) 8 may allow theelongated compartment 2 to be removed from a cooling device. Theelongated compartment 2 is divided into two chambers 3/4 (which may befurther divided symmetrically, e.g., by vertical walls, into four, six,or even eight chambers). The upper chamber 3 and the lower chamber 4 bya narrow section 5 in the middle of the elongated compartment 2.

The elongated compartment 2 contains a freezable liquid 6, comprisingone, two, three, four, or more phase change materials (PCMs). Inoperational form, the upper or first chamber 3 of elongated compartment2, contains the liquid 6, which may then, based on gravity, detect anevent in which cooling is suspended and heating occurs. When thetemperature rises, the liquid 6 moves from the upper first chamber 3 ofthe elongated compartment 2 to the lower or second chamber 4. Agraduation 7 may be included on the elongated compartment 2, on eitheror both of the chamber portions, or upon a shell (not enumerated)encapsulating the elongated compartment 2, to enable measurement of theduration (time) at which food was subjected to suspended cooling,elevated temperature, or the like, e.g., by measuring the level ofmelted liquid 6 collected in the lower or second chamber 4 of theelongated compartment 2. This may allow, for example, an evaluation of afood's validity for consumption.

To reuse the device, the elongated compartment 2, or the measuringdevice with or without the base, may be removed outside the coolingdevice to completely melt the liquid 6 and collect it in the lower(second) chamber 4 of the elongated compartment 2, then restore themeasuring device to its position, or a new position, in the coolingdevice until the liquid freezes/solidifies in the lower (second) chamber4. Thereafter, the elongated compartment 2 is rotated 180° and the lower(second) chamber 4, containing the frozen/solidified liquid 6, isvertically on the top of the elongated compartment, and the formerlyupper (first) chamber 3 of the elongated compartment 2 is brought to thevertical bottom.

Presuming the measuring device to have been frozen such that the firstchamber 3 is vertically above the second chamber 4, if electricity is,for example, cut off or cooling is otherwise suspended, the temperaturewithin the cooling device will eventually increase, i.e., depending uponthermal factors, including heats of fusion and heat capacities of thevolume in the cooled device, heat transfer rates, and the outsideenvironmental temperature, and the liquid 6 will melt. The molten PCMliquid 6 can pass through the narrow section 5 from the upper (first)chamber 3 to the lower (second) chamber 4. The quantity and level ofmelted liquid 6 can be measured using the graduation 7 to determine theduration of the power failure and then the validity of the refrigeratedfood.

FIG. 4 illustrates an inventive device having only a graduation 7 over anon-enumerated shell over the first chamber 3, though the graduation 7may be applied over the second chamber 4, as well or exclusively, or onthe outside of the first and/or second chamber 3/4 or internally in thefirst and/or second chamber 3/4. The duration of suspended cooling canbe evaluated based upon diminution of the PCM liquid 6 volume in thefirst chamber 3. A measuring device as in FIG. 4 has a circular base 1and two joints 8 which allow the shell, including the elongatedcompartment 2, to be removed or rotated about the base on a circularpath with an axis centered on the narrow section 5. To center the devicein the vertical position, four stopper elements 10, e.g., elastomericbumps, may be included on the base 1.

As shown in FIG. 4, the device has a long dimension (shown vertically inFIG. 4) that is substantially greater than a width dimension of theelongated compartment (2). Preferably the length of the elongatedcompartment is at least 5 times the width of the elongated compartment,preferably 5-20, 6-18, 7-16, 8-14 times or 10-12 times the width of theelongated compartment. Overall the device is suitably scaled to fit intoa practically used heating or cooling apparatus and may have a length of0.5-25 cm, preferably 1-20, 2-15, 4-12, or 5-10 cm.

FIG. 5 illustrates an inventive device having graduation 7 within anon-enumerated shell on the first chamber 3 and the second chamber 4.The duration of suspended cooling can be evaluated based upon diminutionof the PCM liquid 6 volume in the first chamber 3 or presence of liquid,optionally re-solidified, in the second chamber 4. This measuring devicehas a square or rectangular base 1 and a single central joint 8 whichallow the shell, including the elongated compartment 2, to be removed orrotated about the base on a circular path with an axis centered on thenarrow section 5. To center the measuring device in the verticalposition, four stopper elements 10, e.g., elastomeric bumps, may beincluded on the base 1. The stoppers 10 may have a pyramidal orhemispheric structure, though the centering function of such stoppersmay be accomplished in the joint, e.g., having metered rotation.

In some embodiments the device is integral with an insulated heating orcooling compartment. For example, the device may include a mountingportion corresponding with (1) of FIG. 5 that is seamlessly incorporatedinto a side wall of the compartment. In this respect the inventionincludes a cooling or heating apparatus comprising an closed interiorcompartment defined by sidewalls, a top and a bottom, at least one ofwhich may function as a door or opening, and each of which is coated orin contact with an insulating material to prevent or hinder ingress oregress of heat or thermal energy. In one embodiment the device ismounted in the compartment so that the elongated compartment (2) in FIG.5 is flush with a plane representing an inner surface of the heating orcooling apparatus. In this respect the device is recessed into theinsulating wall of the heating or cooling apparatus such that no part ofthe device protrudes into the compartment beyond a plane of a wall intowhich the device is seamlessly integrated. Preferably the recess is ovalin shape corresponding with the area of rotation represented by a radiusrepresenting a dimension slightly longer than one half the length of theelongated compartment (2).

FIG. 6 illustrates the measuring device of FIG. 5 in multipletemperature arrays, increasing in temperature form left to right in thefigure, whereby a Galileo thermometer-type system of spheres is presentin the liquid. The typical Galileo thermometer design allows spheres offixed density to rise or fall according to the temperature-basedexpansion (or contraction) of a liquid, and consequent change indensity. This arrangement may enhance a measuring device as disclosedherein, particularly what the restoration of cooling is sufficientlyrapid to trap the spheres in displacement indicative of a thawtemperature. However, alternate approaches contemplated could includenon-miscible or phase-separating PCMs which can take advantage ofdensity changes in two or more PCMs.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

REFERENCE SIGNS

1 base

2 elongated compartment

3 first chamber

4 second chamber

5 narrow section

6 liquid/liquefied PCM

7 graduation

8 joint

9 wall of cooling device

10 stopper

1. A cooling system with defrost indicator, comprising: a cooling devicehaving an insulated interior containment space, and a defrost andtemperature rise indicator mounted on an interior wall of the coolingdevice wherein the defrost and temperature rise indicator comprises: anelongated compartment including a first end and a second end separatedby a side wall along a longitudinal axis of the elongated compartment,thereby forming a cavity including a first chamber and a second chamberthat are fluidly connected through a narrow section located between thefirst and second chambers, wherein at least a portion of the elongatedcompartment is made of a first transparent material; a planar permeablestructure selected from the group consisting of a glass frit, a wirenet, a mesh, and a permeable plastic membrane, disposed at the narrowsection and configured to prevent a movement of a solidified liquid fromone chamber to another when the elongated compartment is verticallyoriented; a liquid, comprising a first phase change material and asecond phase change material, disposed in the cavity; a base to whichthe elongated compartment is releasably and rotatably attached, the basebeing configured to mount the elongated compartment to the interior wallof the cooling device, the defrost and temperature rise indicator beingsubstantially planar in a plane parallel to the interior wall of thecooling device; and a graduation arranged on an outside surface of theelongated compartment suitable for measuring a liquid level in theelongated compartment, wherein the elongated compartment is configuredto be rotated about a central axis orthogonal to the base, the first andsecond chambers being symmetric about the central axis, wherein thefirst and second chambers are symmetric to each other, and wherein thedefrost and temperature rise indicator is configured to determine adefrost or temperature rise period for two or more temperature intervalsin the insulated interior containment space of the cooling device. 2.(canceled)
 3. The cooling system of claim 1, wherein the firsttransparent material comprises quartz, glass, polyethyleneterephthalate, polybutylene terephthalate, polyacrylate,polymethacrylate, polyethylene, polypropylene, polyvinyl chloride,polyethernitrile, polyethersulfone, polystyrene, polycarbonate,polymethylmethacrylate, styrene-acrylonitrile, styrene-methylmethacrylate, methyl methacrylate-butadiene-styrene, or a two or more ofany of these, and wherein the liquid comprises water and furthercomprises a coloring dye. 4-6. (canceled)
 7. The cooling system of claim1, wherein the base includes a single joint about which the elongatedcompartment is configured to rotate.
 8. (canceled)
 9. The cooling systemof claim 1, wherein the first phase change material and the second phasechange material are each a hydrocarbon.
 10. The cooling system of claim1, wherein the first phase change material is an inorganic salt, andwherein the second phase change material is water.
 11. The coolingsystem of claim 1, wherein the first phase change material is an organicsalt, and wherein the second phase change material is water.
 12. Thecooling system of claim 1, wherein the liquid further comprises a thirdphase change material
 13. The cooling system of claim 1, wherein the twoor more temperature intervals are in a range of from −20 to 10° C., andare spaced by at least 5° C.
 14. The cooling system of claim 1, whereinall phase change materials in the liquid are miscible. 15-16. (canceled)17. The cooling system of claim 1, wherein base comprises a magnetconfigured to attach the defrost and temperature rise indicator to theinterior wall of the cooling device. 18-20. (canceled)
 21. The coolingsystem of claim 1, wherein the cavity includes only the first chamberand the second chamber.
 22. The cooling system of claim 1, wherein thebase includes at least two stopper elements on opposing sides of thefirst or second chambers, the at least two stopper elements protrudingin a direction orthogonal to the base, and being configured tovertically center the elongated compartment.